This invention relates to recording medium control device and method suitably used for carrying out high-speed and flexible control of write and read with respect to various recording medium pieces.
The present Assignee has proposed a device which can provide various information by transferring information such as sounds, images, characters, and programs from an information providing device (information transfer device) to a recording device or a recording/reproducing device having a semiconductor memory or the like enclosed therein, in the Japanese Publication of Unexamined Patent Application No. Hei 6-131371, No. Hei 6-215010, and No. Hei 6-301601.
FIG. 1 is a view showing appearance of a conventional information recording/reproducing device proposed in the above-mentioned publications. This information recording/reproducing device 200A has a connection terminal 201 for connection with an information providing device, not shown, and is capable of copying information from the information providing device through the connection terminal 201 to a recording medium provided in the information recording/reproducing device 200A. Although the type of the recording medium is not particularly limited, it is convenient to use a semiconductor memory which enables high-speed copying and which is randomly accessible and excellent in portability.
This information recording/reproducing device 200A is provided with a display unit 202 for displaying characters and images, and a function selecting section 203 constituted by pushbutton switches. Since this information recording/reproducing device 200A displays the contents of information recorded in the recording medium onto the display unit 202, the user can selectively reproduce desired information by using the function selecting section 203.
The contents of information provided from the information providing device includes text information, audio information, video information, and computer programs, and is not particularly limited. Reproduction of a program means execution of the program. However, in this case, the user may input information at the time of execution, if necessary. In the case where reproduction signals are text information or video signals, the signals can be displayed on the display unit 202 constituted by, for example, a liquid crystal display device. In addition, in the case of audio information, the information can be outputted to an earphone 204. Although not shown, a speaker may be provided in place of or in addition to the earphone 204, or an output terminal for reproduction signals may be provided to enable connection with an external display device or speaker.
FIG. 2 is a view showing appearance of another conventional information recording/reproducing device proposed in the above-mentioned publications. An information recording/reproducing device 200B shown in FIG. 2 is constituted by splitting the information recording/reproducing device 200A of FIG. 1 into an information recording device 210 and an information reproducing device 220. In this information recording/reproducing device 200B, information from the information recording device 210 can be transmitted and reproduced on the side of the information reproducing device 220, by inserting the information recording device 210 into an insertion/ejection port 221 of the information reproducing device 220.
For reproduction, data and control signals must be transmitted between the information recording device 210 and the information reproducing device 220. Therefore, a connection terminal 212 for connection with the information reproducing device 220 is provided on the information recording device 210, and a connection terminal corresponding to this connection terminal 212 is provided on the information reproducing device 220, so that these two connection terminals are connected with each other in the state where the information recording device 210 is mounted in the information reproducing device 220.
The information recording device 210 has two connection terminals, that is, a connection terminal 211 for connection with the information providing device and the connection terminal 212 for connection with the information reproducing device. However, a single terminal may be used in a switching manner.
The information recording device 210 can be constituted only by a recording medium. By using only the recording medium, a portable information recording device of small size and light weight is provided. In this case, control of reading from the recording medium and writing to the recording medium is carried out on the side of the information reproducing device 200 or the information providing device.
FIG. 3 is a view showing appearance of a conventional information providing device proposed in the above-mentioned publication. This information providing device 230 has a display unit 231 for displaying the contents and price of available information, and an output selecting section 232 for the user to select desired information. By inserting the information recording device 210 shown in FIG. 2 into an insertion/ejection port 233 of the information providing device 230, and then operating the output selecting section 232 to select desired information with reference to information displayed on the display unit 231, the user can copy the desired information to the information recording device 210. Also, the user can copy information by connecting a connection terminal provided on the information providing device 230 to the connection terminal 201 of the information recording/reproducing device 200A shown in FIG. 1.
The information providing device 230 has a recording medium storing therein information to be provided, and an information copy control section (not shown) for writing read-out information to the information recording device 210 and the information recording/reproducing device 200A. There may also be provided a structure in which the information providing device 230 and an information providing center, not shown, are connected to each other via a wire or a wireless communication section to provide information desired by the user through the communication section. By providing such structure, the recording medium need not be provided in the information providing device 230. Even in the case where the recording medium is provided in the information providing device 230, by updating the information stored in the recording medium through the communication section, the latest information can be provided while the communication cost is restrained.
FIG. 4 is a view showing appearance of another conventional information providing device proposed in the above-mentioned publications. This information providing device 240 has an insertion port 241 and an ejection port 242 for the information recording device 210 which are arranged away from each other at a certain distance. This information providing device 240 has a moving section, not shown, for transporting the information recording device 210 inserted from the insertion port 241, and after copying information to be provided to the inserted information recording device 210, the information providing device 240 ejects the information recording device 210 from the ejection port 242. A person H who wishes to obtain information can receive copied information while walking in a direction of A in FIG. 4. This information providing device 240 can quickly provide information to a number of people.
As a recording medium used in the case where the information recording/reproducing device needs to have portability, it is desired to use a non-volatile memory which does not require backup of information by a battery. That is, it is convenient to use the non-volatile memory since erasure of recorded information can be prevented. As such non-volatile memory, for example, an EEPROM (electrically erasable programmable read-only memory), described in Iwata, et al. , xe2x80x9c32 Mbits NAND flash memory,xe2x80x9d Electronic Materials, June 1995, pp.32-37, can be used.
Conventionally, there is also DMA (direct memory access) as a method for directly transferring data without using a CPU (central processing unit), and a DMA controller (hereinafter referred to as DMAC) is employed as a dedicated circuit for realizing this method. This method is used in the case where a large quantity of data needs to be transferred at a high speed, for example, in data transmission to an auxiliary memory device such as a hard disk drive or in image processing in which image data are handled.
FIG. 5 shows an example of the structure of the conventional information recording/reproducing device. Such example can be seen in the case where DMA transfer is carried out between an I/O device such as a hard disk controller or a SCSI (small computer system interface) and a memory such as a magnetic disk or an SRAM (static random access memory).
A DMAC 251 of an information recording/reproducing device 250 includes an address register p which indicates the address of a transfer destination such as a memory and in which increment (+1) is made for each data transfer, and a word counter c which calculates the number of words of transfer data and in which decrement (xe2x88x921) is made for each data transfer. The initial values thereof are set by a CPU 252 prior to DMA transfer.
DMA transfer is started by a data transfer request from an I/O device 254. The I/O device 254 sends to the DMAC 251 a signal DREQ for requesting data transfer in order to carry out data transfer with the above-described information providing device through a data input/output terminal 255. On receiving this signal, the DMAC 251 sends to the CPU 252 a signal BUSREQ for requesting right of bus use in order to acquire the right of use of a bus, which is normally occupied by the CPU 252. On receiving this signal, the CPU 252 completes necessary processing such as interrupting execution of a program, and then sends back to the DMAC 251 a signal BUSACK indicating release of the bus. Thus, it is recognized that the DMAC 251 has acquired the right of bus use, and actual data transfer is started using the DMAC 251 as a bus master.
An address bus and a data bus indicated by dotted lines in FIG. 5 denote portions to be used in the case where the right of bus use is exercised using the CPU 252 as a bus master, and obtain high impedance once the right of bus use is released. Therefore, the DMAC 251 can carry out DMA transfer by using an address bus and a data bus indicated by solid lines in FIG. 5.
At this point, the DMAC 251 sets the I/O device 254 in a DMA transfer enable state by a response signal DACK to the DMA transfer request from the I/O device 254, and at the same time, sets a memory 253 in an enable state by a chip enable signal CE. At the same time, the DMAC 251 inputs an address indicated by the address register p to the memory 253 through the address bus.
DMA transfer for one word is carried out as follows. In the case of data transfer from the I/O device 254 to the memory 253, both an I/O device read signal IOR and a memory write signal MEMW are activated. On the other hand, in the case of data transfer from the memory 253 to the I/O device 254, both a memory read signal MEMR and an I/O device write signal IOW are activated. A signal appearing on the data bus at this point becomes data to be transferred.
Every time one word of data is transferred, increment is made on the value of the address register p, and at the same time, decrement is made on value of the word counter c. DMA transfer is continuously carried out until the value of the word counter c becomes 0 or the DMA transfer request DREQ from the I/O device 254 is withdrawn. In any case, at the same time as the end of DMA transfer, the DMAC 251 withdraws the right of bus use request signal BUSREQ outputted to the CPU 252, and the CPU 252 recognizing this withdrawal withdraws the right of bus use release signal BUSACK, thereby resuming interrupted processing.
As described above, DMA transfer is adapted for realizing effective use of a bus band. It enables execution of data transfer in a burst-like manner, which is time-consuming if carried out through the CPU, and also enables the bus master other than the CPU to carry out efficient control of the memory and the I/O device without lowering performance of the CPU.
Meanwhile, in the case where the information recording/reproducing device is constituted by a hard disk drive or a PC card, initially, a file is recorded at physical continuous recording positions of a recording medium. However, as rewrite of the file is repeated, the file will be split and recorded at physically separated positions.
With the DMAC described in the conventional technique, in the case where data constituting a file to be read out are scattered in the memory or conversely in the case where a file must be recorded into free areas scattered in the memory, transmission/reception of the right of bus use and reset of the DMAC must be carried out through the CPU for each data split into an arbitrary length. There is a possibility that such overhead processing increases in proportion to the degree of scattering of data and significantly lowers the efficiency of data transfer.
To improve the efficiency of data transfer, it is conceivable to introduce a parallel control system for a plurality of recording medium pieces as proposed and described in the specification and drawings of the Japanese Publication of Unexamined Patent Application No. Hei 7-200181 by the present Assignee. The technique proposed in the specification and drawings of the Japanese Publication of Unexamined Patent Application No. Hei 7-200181 realizes highly efficient information transfer by simple control, by carrying out parallel writing in a regular order with respect to a plurality of recording medium pieces in an information recording device constituted by a recording medium such as a flash memory in which the write speed is not uniform depending on each recording unit. However, also in the technique proposed in the specification and drawings of the Japanese Publication of Unexamined Patent Application No. Hei 7-200181, with the DMAC of the conventional technique, overhead processing during data transfer as described above is necessary for each data of an arbitrary length constituting the file. Although a delay before the start of transfer is allowed to a certain extent with respect to real-time data such as music or a picture, a delay after the start of transfer lacks temporal correctness and becomes a serious problem causing generation of noise or fluctuation of picture.
Also, as the performance of the DMAC other than the data transfer speed, capability for carrying out data transfer independent of the recording medium and the recording format is required. In short, it is desired to flexibly cope with the case where the structure and type of recording media vary or the case where the recording position and recording order vary.
Thus, in view of the foregoing status of the art, it is an object of the present invention to provide recording medium control device and method which are adapted for carrying out high-speed data transfer by parallel control of recording medium pieces while restraining overhead processing in data transfer and which enable data transfer of high versatility.
A recording medium control device according to the present invention includes a plurality of ordered address registers for holding address values with respect to a recording medium on which information can be recorded, a pointer for sequentially selecting one effective address register from the plurality of address registers, and a control circuit for carrying out control to output the address value of the address register indicated by the pointer and a control signal to the recording medium so as to carry out parallel control with respect to a plurality of addresses in the recording medium.
Also, a recording medium control device according to the present invention includes an address register for holding an address value with respect to a recording medium constituted by a plurality of recording medium pieces on which information can be recorded, a selection circuit for generating a recording medium selection signal corresponding to each of the plurality of recording medium pieces on the basis of the address value, and a control circuit for carrying out control to output the address value, the recording medium selection signal and a control signal to the recording medium piece so as to carry out control with respect to the plurality of recording medium pieces.
In addition, a recording medium control device according to the present invention includes an address register for holding an address value with respect to a recording medium on which information can be recorded, and a control circuit for carrying out control to output the address value of the address register and a control signal to the recording medium and for changing control with respect to the recording medium in accordance with the value of the address register.
A recording medium control method according to the present invention includes the steps of sequentially selecting one effective address register from a plurality of ordered address registers for holding address values with respect to a recording medium on which information can be recorded, and carrying out control to output the address value of the selected address register and a control signal to the recording medium so as to carry out parallel control with respect to a plurality of addresses in the recording medium.
Also, a recording medium control method according to the present invention includes the steps of holding an address value with respect to a recording medium constituted by a plurality of recording medium pieces on which information can be recorded, generating a recording medium selection signal corresponding to each of the plurality of recording medium pieces on the basis of the address value, and carrying out control to output the address value, the recording medium selection signal and a control signal to the recording medium piece so as to carry out control with respect to the plurality of recording medium pieces.
In addition, a recording medium control method according to the present invention includes the steps of holding an address value with respect to a recording medium on which information can be recorded, and carrying out control to output the address value and a control signal to the recording medium while changing control with respect to the recording medium in accordance with the address value.